CFD技术在果树风送喷雾中的应用与前景分析

为了分析计算流体动力学(CFD)模型在果园风送式喷雾技术中的应用现状,探究了CFD技术在风机结构优化(包括叶片数、倒流结构、叶片受力、叶片安装角和风筒结构等)与性能预测(效率、噪声)方面的广泛应用,验证了k-ε标准模型的应用成熟性;此外,CFD技术在喷雾微观特性研究的应用验证了拉格朗日法研究气相与离散相相互作用的有效性,但目前研究还不能提供一次雾化机理的相关信息;在果树冠层内流场及药液沉积方面,验证了k-ε标准模型的适应性,但果树冠层对气流的湍流动能耗散研究不细致,而且缺乏雾滴在冠层中的沉积模型研究.文中展望了今后在风机结构优化与性能预测、雾化机理及果树冠层对喷雾气流的影响等方面的发展前景,提出与果树冠层特征相匹配的喷雾量与风速是未来的研究热点.

Application of CFD technology in air-assisted spraying in orchard and analysis of its prospects

With the rapid development of numerical computational theory and computer technology, CFD technology has been extensively used in agricultural engineering to vividly visualize flows. This review mainly focused on applications of CFD technology in structure optimization(number of blades, backflow structure, stress in blade, blade angle and duct configuration)and performance prediction(efficiency and noise)of fans in air-assisted sprayer as well as validation of standard k-ε turbulence model. Additionally, the feasibility of Lagrangian method for handling interaction between air and disperse phase is verified by applying CFD technology to identify microscopic characteristics of spray. Unfortunately, CFD technology cannot provide any information about atomization mechanism of spray pre-sently. The standard k-ε turbulence model has been applied and verified in internal flow and droplet deposition on canopy. However, the effects of canopy on turbulent kinetic energy dissipation are not explored in detail, and there is lack of study on droplet deposition model. Finally, a few prospects for structure optimization and performance prediction of fans, atomization mechanism and effects of canopy on spraying flow are highlighted. Furthermore, it is proposed that how to determine the spray capacity and velocity which can match a specific canopy should be the hotpot problem in future.